304 
Mycologia 
Delacroix, these spores are wind disseminated ; but as they are in 
a somewhat sticky mass at first, insects or birds might carry them, 
as in the case of the chestnut-blight fungus (Endothia parasitica 
(Murrill) Anderson & Anderson) as reported by Heald and 
Studhalter (3), and Studhalter and Ruggles (5). 
Effect of the Disease on Poplars 
Dothichisa popitlea at first kills a few limbs here and there on 
younger trees in the nursery rows. The cankers on such trees, 
owing to the fact they are not conspicuous at first, are easily 
overlooked. When the disease becomes well established many of 
the lower limbs are killed and rapidly growing sprouts are sent 
up from the bases of the trees below the cankered areas. These 
sprouts, though vigorous, are soon infected by the fungus and 
are likely to be removed and used for cuttings, under the impres- 
sion that they are healthy. 
On older trees in nursery rows and on well-established shade 
trees the lower limbs are killed by the fungus and scars are soon 
formed by cankers on the trunks, which are thereby rendered 
unsightly. At the same time tufts or clusters of rapidly growing 
sprouts are sent out near or below diseased areas. These in turn 
are killed by the fungus, which gradually spreads to all parts of 
the tree, finally killing it. 
In case of freshly transplanted trees, the disease is much more 
virulent. Cankers may encircle either the trunks or main limbs 
of the trees, killing them. In the case of black poplars, the beau- 
tiful tapering cone-shaped outline of the tree is destroyed. Trees 
once attacked apparently never recover their' former beauty, even 
where the dead parts have been carefully removed. 
In France, Delacroix (2) reports the disease as especially se- 
vere on nursery stock and younger trees and of less importance 
on old-established trees. There, as in the United States, it de- 
stroys the beauty of the black poplars. It also causes consider- 
able loss to growers of Canada poplars who raise the trees for 
saw logs. 
The disease in Europe is reported both by Delacroix (i, 2) and 
by Voglino (6, 7, and 8) as especially severe on Canada poplars, 
but in the United States, so far, it has been found in a serious 
form only on black poplars. 
